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HelpTest ID LPALD Lipoprotein (a) and Low-Density Lipoprotein Cholesterol, Serum
Specimen Required
Patient Preparation:
1. Fasting (8 hours) required
2. Patient must abstain from alcohol for 24 hours before collection.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 4 mL
Collection Instructions:
1. Centrifuge and aliquot serum into a plastic vial.
2. Send refrigerated.
Useful For
Evaluation of the contribution of lipoprotein (a) (Lp[a])-cholesterol within measured low-density lipoprotein cholesterol
Evaluation of increased risk for cardiovascular disease and events:
-Most appropriately measured in individuals at intermediate risk for cardiovascular disease
-Patients with early atherosclerosis or strong family history of early atherosclerosis without explanation by traditional risk factors should also be considered for testing
-Follow-up evaluation of patients with elevations in Lp(a) mass
Method Name
Lipoprotein (a) Cholesterol: Electrophoresis/Enzyme Staining/Densitometry
Low-Density Lipoprotein Cholesterol: Ultracentrifugation/Selective Precipitation/Enzymatic Colorimetric (Beta-Quantification)
Reporting Name
Lp(a) and LDL Cholesterol, SSpecimen Type
SerumSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 60 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | Reject |
Clinical Information
The cholesterol within lipoprotein(a) (Lp[a]) is included in every method that measures low-density lipoprotein cholesterol (LDL-C). Therefore, in patients that express high concentrations of Lp(a) the interpretation of LDL-C and the resulting clinical diagnoses and treatment strategies may be inaccurate. This panel reports 3 values: 1) the cholesterol measured within LDL by beta quantitation (this result contains both LDL-C and Lp[a]), 2) the cholesterol within Lp(a), and 3) a calculated "true" LDL-C where Lp(a)-C is subtracted from the beta quantitation LDL-C.
The abnormal lipoprotein-X (LpX) is visible on lipoprotein electrophoresis. If LpX is present, the measurement of LDL-C is inaccurate and will not be reported.
Reference Values
Lipoprotein (a) Cholesterol: Normal: <5 mg/dL
Lipoprotein-X: Undetectable
Low-Density Lipoprotein Cholesterol (LDL-C):
The National Lipid Association and the National Cholesterol Education Program (NCEP) have set the following guidelines for LDL-C in adults (ages 18 years and older):
Desirable: <100 mg/dL
Above desirable: 100-129 mg/dL
Borderline high: 130-159 mg/dL
High: 160-189 mg/dL
Very high: ≥190 mg/dL
The Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents has set the following guidelines for LDL-C in children and adolescents (ages 2-17 years):
Acceptable: <110 mg/dL
Borderline high: 110-129 mg/dL
High: ≥130 mg/dL
Interpretation
Results of this panel can be used to determine the cholesterol content of low-density lipoprotein (LDL) and lipoprotein (a) (Lp[a]) separately. Interpretations of lipoprotein disorders can be made within the other clinical context.
Lipoprotein-X (LpX) is an abnormal lipoprotein that appears in the sera of patients with obstructive jaundice and is an indicator of cholestasis. The presence of LpX will be reported if noted during Lp(a) cholesterol analysis. The other values (LDL-C and Lp(a)-C) will not be reported if LpX is present.
Cautions
Lipoprotein (a) (Lp[a]) cholesterol values should not be confused with Lp(a) mass values, although they may be correlated in some individual cases. Lp(a) cholesterol values will be approximately 10 times lower than Lp(a) mass values, but the difference between the measures is not uniform. Lp(a) mass values are considered elevated when greater than 30 mg/dL. Lp(a) cholesterol is increased if greater or equal to 5 mg/dL.
Intravenous administration of heparin causes activation of lipoprotein lipase, which tends to increase the relative migration rate of the fractions, especially beta lipoproteins.
Clinical Reference
1. Fatica EM, Meeusen JW, Vasile VC, Jaffe AS, Donato LJ. Measuring the contribution of Lp(a) cholesterol towards LDL-C interpretation. Clin Biochem. 2020;86:45-51. doi:10.1016/j.clinbiochem.2020.09.007. Erratum in: Clin Biochem. 2021;88:56-57
2. Willeit P, Yeang C, Moriarty P, et al. Low-density lipoprotein cholesterol corrected for lipoprotein (a) cholesterol, risk thresholds, and cardiovascular events. J Am Heart Assoc. 2020;9(23):e016318
3. Yeang C, Witztum JL, Tsimikas S: 'LDL-C'=LDL-C+Lp(a)-C: implications of achieved ultra-low LDL-C levels in the proprotein convertase subtilisin/kexin type 9 era of potent LDL-C lowering. Curr Opin Lipidol. 2015;26(3):169-178. doi:10.1097/MOL.0000000000000171
4. Kinpara K, Okada H, Yoneyama A, Okubo M, Murase T. Lipoprotein(a)-cholesterol: a significant component of serum cholesterol. Clin Chim Acta. 2011;412(19-20):1783-1787. doi:10.1016/j.cca.2011.05.036
5. Yeang C, Willeit P, Tsimikas S. The interconnection between lipoprotein(a), lipoprotein(a) cholesterol and true LDL-cholesterol in the diagnosis of familial hypercholesterolemia. Curr Opin Lipidol. 2020;31(6):305-312. doi:10.1097/MOL.0000000000000713
Method Description
Lipoprotein (a) Cholesterol:
Electrophoretic separation of lipoproteins followed by lipid staining and densitometry measurement.(Package insert: SPIFE Vis Cholesterol Reagent. Helena Laboratories; 09/2015)
Low-Density Lipoprotein Cholesterol:
Serum is combined with dextran sulfate and magnesium, ions precipitate the low-density lipoprotein and very low-density lipoprotein fractions, leaving the high-density lipoprotein (HDL) fraction in solution. The HDL cholesterol is then determined using an enzymatic cholesterol assay.(Package insert: HDL Cholesterol Precipitating Reagent Set (Dextran Sulfate). Pointe Scientific, INC; 12/2009)
Cholesterol esters are cleaved by the action of cholesterol esterase to yield free cholesterol and fatty acids. Cholesterol oxidase then catalyzes the oxidation of cholesterol to cholest-4-en-3-one and hydrogen peroxide. In the presence of peroxidase, the hydrogen peroxide formed effects the oxidative coupling of phenol and 4-aminophenazone to form a red quinone-imine dye. The color intensity of the dye formed is directly proportional to the cholesterol concentration. It is determined by measuring the increase in absorbance.(Package insert: Roche Cholesterol Gen 2 Reagent. Roche Diagnostics; V 16.0, 10/2023)
Day(s) Performed
Monday through Thursday, Sunday
Report Available
3 to 4 daysTest Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83700
83701
NY State Approved
YesForms
If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen.